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Radiation Therapy


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Radiation therapy (also known as radiotherapy) uses targeted, high-energy X-rays to kill cancer cells. The goal of radiation therapy is to kill any cancer that might be left in or around the breast.  

Radiation therapy after surgery is an option for most women who have ductal carcinoma in situ (DCIS, non-invasive breast cancer), early stage breast cancer, locally advanced breast cancer or inflammatory breast cancer.

Radiation therapy and non-invasive breast cancer

Radiation therapy is usually given to women who are treated with lumpectomy for DCIS. It is not given to women treated with mastectomy for DCIS.  

Learn more about treatment for DCIS.  


For a summary of research studies on lumpectomy plus radiation therapy in the treatment of DCIS, visit the Breast Cancer Research section.

Radiation therapy and invasive breast cancer

Radiation therapy after lumpectomy

For most women, radiation therapy is needed after lumpectomy (also called breast conserving surgery), since much of the breast tissue is left intact. It lowers the chances of breast cancer recurrence by about 50 percent and lowers the chances of breast cancer death by about 20 percent [4].

Radiation therapy after mastectomy

Many women who have a mastectomy do not need radiation therapy. However, in some cases, radiation is used after mastectomy to treat the chest wall and the lymph nodes around the collarbone and in the underarm area (axillary nodes).

Who is eligible for radiation therapy?

Not everyone can have radiation therapy. Being pregnant or having certain health conditions can make radiation therapy harmful.

  • Pregnancy. Radiation can harm a fetus, so it is not usually given during pregnancy. However, in some cases, a woman may be able to have a lumpectomy and postpone radiation therapy until after delivery.
  • Active scleroderma or systemic lupus. These disorders can keep tissue from healing correctly after radiation therapy. (In some cases, radiation therapy may still be used.)
  • Past radiation therapy to the same breast. In general, radiation therapy to the breast can only be given once. (In rare cases, radiation to the same breast may be repeated.)

Radiation therapy and breast implants

Women who have breast implants (both saline and silicone) can usually have radiation therapy. However, implants can make radiation therapy planning more complex. Radiation can cause scarring and hardening of the implant, leading to a less natural look.  

If your treatment plan includes mastectomy, radiation therapy and breast reconstruction, discuss possible risks with your breast surgeon and radiation oncologist.  

Learn more about breast reconstruction.

Radiation therapy guidelines

Although the exact treatment for breast cancer varies from person to person, treatment guidelines help ensure quality care. These guidelines are based on the latest research and the consensus of experts. The National Comprehensive Care Network (NCCN) and American Society of Clinical Oncology (ASCO) are two respected organizations that regularly update and post their guidelines online. The National Cancer Institute (NCI) also has overviews of treatment options.

Importance of following your breast cancer treatment plan

The importance of adherence (compliance)

Breast cancer treatment is most effective when all parts of the treatment plan are followed. Adherence (also called compliance) is how closely people follow the treatment plan (for medications and other therapies) prescribed by their health care providers in terms of:

  • Timing
  • Dose
  • Frequency

Completing radiation therapy after lumpectomy

Radiation therapy after lumpectomy lowers the risk of breast cancer recurrence and increases the chances of survival [4,12]. In most cases, it is needed after lumpectomy.  

Radiation therapy for early breast cancer usually involves treatment five days a week for three to seven weeks. Getting to and from the treatment center this many times can be hard, especially if you live far away. If you a need ride to and from treatment, often there are resources that can help. Family and friends often want to help, but do not know how. This is a way they can help you. And, some organizations offer programs to assist with transportation. Others offer lodging if you need a place to stay overnight so that you can get treatment.  

Don’t hesitate to ask for help from your co-survivors or contact organizations that offer help with transportation or lodging. It is important is to complete your radiation therapy without long gaps or delays.  

Learn more about adherence

Updated 03/28/14

  Treatment Introduction 
Going Through Radiation Therapy  next 
Side Effects of Radiation Therapy  next 
Emerging Areas in Radiation Therapy  next 
Questions for Your Provider-Radiation Therapy  next 

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